The present invention relates to light emitting diode (LED) lamps, and more particularly to individual lenses to redirect light from LED lamps for various applications, such as LED traffic signal lamps, LED display boards, LED light bulbs, LED clusters, and LED signs.
Light Emitting Diode (LED) lamps have been developed to replace the conventional incandescent or fluorescent lamps to reduce electrical cost and increase reliability. LED lamps consume less energy than convention lamps while exhibiting much longer lifetimes. Such lamps are typically made by mounting a plurality of LEDs to a flat printed circuit board (PCB), with the flat surface of the PCB on which the LEDs are mounted facing toward the desired direction of the light output.
Typical LEDs are manufactured to emit most of their light output primarily in the axial direction of the LED, and within a relatively small viewing angle. Therefore, lamps with a flat PCB primarily emit light in a direction perpendicular to the flat surface on which the LEDs are mounted.
There are certain applications, however, where it is desired to direct at least some of the light output away from, and possibly unsymmetrically with respect to, the axial direction of the LEDs. For example, overhead traffic signal LED lamps face parallel to the ground and therefore emit most of the light output parallel to the roadway, which is viewable by drivers located far away from the intersection. However, not much light is directed downwardly toward drivers closer to or at the intersection.
Another drawback of LED lamps is that a significant amount of light is also emitted out the sides of each LED. This side emitted light is wasted because it is not directed into the desired viewing angle of the LED lamp.
Oval LEDs have been developed to try and direct the light from the LED lamp in a larger, unsymmetrical viewing angle (i.e. evenly along the roadway for a traffic signal LED lamp). However, oval LEDs are often too complex and costly to manufacture and/or assemble. Further, the LEDs and the LED lamp must be carefully oriented to direct the light in the desired directions. Variable adjustment of the light distribution pattern is not possible.
Lens designs have also been used to direct the LED output distribution in a more desirable way. For example, U.S. Pat. Nos. 5,636,057, 5,174,649 and 5,833,355 disclose single prismatic toroidal lenses in front of an LED array to direct the light toward a plurality of predetermined, distinct spatial points. Each lens piece consists of many elements that line up with the individual LEDs. The design of such elements can vary depending on the application. However, such lenses are not versatile. If the desired output distribution changes, or if the LED lamp configuration changes (i.e. changing the number or arrangement of LEDs), the lenses must be redesigned and replaced. There simply is no way to make minor adjustments to the light distribution as the need arises, which is a problem because as LED technology improves, the arrangement and the number of LEDs used in many applications, such as traffic signal lights, will change. In addition, the lens must be precisely aligned to the LED lamp for maximum effect so that the individual elements are properly aligned to the corresponding LED output. Another drawback with such lens designs is that, for certain applications such as a very large display board, manufacturing a large piece of lens becomes impractical.
There is a need for an LED lamp lens design that can efficiently, and preferably adjustably, redirect the output of LEDs without having to use a single lens structure for the entire LED lamp. Such a lens design should accommodate changes in the desired output distribution pattern from the lamp, or changes in the number and arrangement of LEDs, as the needs of a particular application change.
The present invention solves the aforementioned problems by providing each individual light emitting diode (LED) with a lens tailored to fit each specific application.
The LED lamp of the present invention includes a circuit board, a plurality of LEDs mounted to the circuit board that when activated emit a light output, and a plurality of LED covers each mounted to cover one of the plurality of LEDs. Each LED cover includes a lens portion that redirects the light output from the one LED.
In another aspect of the present invention, the LED lamp of the present invention includes a housing, a circuit board mounted to the housing, an electrical connector attached to the housing and electrically connected to the circuit board, a plurality of LEDs mounted to the circuit board that are activated to emit a light output when an electrical voltage is applied to the electrical connector, and a plurality of LED covers each mounted to cover one of the plurality of LEDs. EachLED cover includes a lens portion that redirects the light output from the one LED, and a side portion that attaches to one of the PCB and the one LED to secure the LED cover in place.
Other objects and features of the present invention will become apparent by a review of the specification, claims and appended figures.